Current estimates place the total area of possibly unexploded ordnance (UXO) contaminated sites at approximately 10 million acres. The overall cost of remediation of these sites with current methods and sensing technologies would most likely reach into the tens of billions of dollars. Studies have estimated that up to 80% of typical sites of potential contamination are actually UXO-free. Therefore, there is a need to quickly and reliably scan large sites (on the order of 10,000 acres) in order to rapidly identify regions that are free of UXO and regions that must be subjected to more detailed and time-intensive examination and remediation with established UXO detection tools.
Effective wide-area UXO assessment is centered on the capability to rapidly scan large tracts of land and obtain relevant, useful information in the process. Two possible modes of enhancement to wide-area UXO assessment are, first, decreasing the false alarm rate of current UXO sensing technologies, and second, utilizing alternate sensing technologies and survey methods that scan larger areas or more rapidly cover large areas than current sensing platforms.
In the conventional art, standard, ground-based UXO sensing technologies include methods such as vehicular-mounted time and frequency domain electromagnetic induction (EMI), total field magnetometry (TFM), and ground penetrating radar (GPR). These UXO sensors have been deployed on ground-based platforms such as portable devices, push carts, and towed sensor arrays. Standard analysis methods of these types of data are well described in the prior art. These methods typically rely on generating theoretical sensor response models, or measuring pure responses of various UXO items and then comparing survey data to these models in order to make a detection or classification. However, typically, the ability of such techniques to cover wide survey areas is limited.
Furthermore, as the sensitivity/ground penetration depth of direct UXO sensing technologies, such as magnetometry, drops steeply with distance, alternate techniques for wide-area assessment will generally not have the benefit of sensing deeply buried UXO objects directly. Instead, they must rely on sensing UXO-related phenomena like spectral chemical signatures, variations in heat capacity, and measurements of surface clutter and microtopological features. The techniques of synthetic aperture radar (SAR), light detection and ranging (LiDAR), and high-resolution aerial photography all yield information about microtopological features and surface clutter of wide areas under assessment. These sensors have the benefit of functioning over much greater distances than electromagnetic sensors, allowing them to be deployed on fixed wing aircraft.
Wide-area sensing platforms are typically designed and optimized to detect UXO or UXO-related features without correlation to other sources of data or expert information. Data are acquired and processed via feature extraction, manual inspection and feature identification. Final site assessment is provided by evaluating the extracted UXO-related features, taking into account a priori knowledge as to how accurate the features are at indicating the presence of UXO and/or UXO-related objects. Thus, two types of information are obtained from sensing: UXO-related features extracted from survey data, and meta-data regarding the relationship between UXO and these features. Further information can be obtained from manual assessment of the site. Areas associated with UXO-related activities can be delineated through visual inspection of sensing data or through knowledge of historical usage patterns at the site. Examples of this type of information include delineations of visible bombing targets and descriptions of known munitions ranges. Thus, in the conventional art, at each survey site, site managers can potentially have multiple, disparate lines of evidence for or against the presence of UXO or UXO-related items, without a way to combine these different forms of evidence to make a more delineation of areas of likely UXO contamination.
Accordingly, there remains a need for a method or system that can utilize all the available evidence for or against the presence of UXO or UXO-related items, and in turn, allow site managers to more accurately delineate areas of likely UXO contamination.